Without a doubt, the SIG SAUER MPX rifle is one of the coolest things to be unveiled in the last couple years. It’s a pistol caliber carbine that has all of the same controls as an AR-15 and feels just ever-so-pleasant to hold. But while the gun itself is cool, one of the best things about it is that the civilian version has the same barrel length as the military and law enforcement versions, but with a gigantic muzzle brake out front to bring it up to the required 16″ in length. And not only is it a functional muzzle brake, SIG claims that you could buy a shroud for the brake later on a form 4 that slots over it to turn it into a silencer. Except there’s a problem . . .

The ATF didn’t like it. They saw it as a baffle stack, not a muzzle brake and as such classified it as a silencer. From a press release:

The Newington gun maker’s suit, filed in the U. S. District Court of New Hampshire, states that it submitted a rifle, with its muzzle brake, to the ATF on April 4, 2013 for evaluation. The device is described as 9.5 inches long and permanently attached with a weld to a 6.5 inch barrel, making the overall barrel length 16 inches.

The ATF responded, by letter dated Aug. 26, 2013, that the device is constructed as a silencer component commonly referred to as a “monolithic baffle stack,” the suit states. “Welding it to a barrel does not change its design characteristics or function,” Sig says it was informed by the ATF.

In a Sept. 6, 2013 followup letter, Sig asked the federal regulatory agency for reconsideration, while reporting that sound meter testing proved the device amplified, not muffled sound, when a gun with it was fired. It also included evidence showing the device offsets and corrects recoil of a firearm when attached, Sig claims.

You can't be in possession of suppressor parts without the paperwork, regardless of whether you even have a firearm. Seems like an expensive advertisement campaign for Sig.

NRA Life Member, NRA Certified Instructor: HFS, Pistol, Rifle, PPIH,PPOH
Suarez Combat Arms Instructor School
Admit nothing. Deny everything. Demand proof.
If we lie to the government, it's a crime. If the government lies to the people, it's called politics.
Paying for welfare is slavery.

The term “Firearm Silencer” or “Firearm Muffler” means any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for the use in assembling or fabricating a firearm silencer or firearm muffler, any part intended only for use in such assembly or fabrication.

Ok, so using the Feds definition, Sig is basing their argument on the word 'parts'. Since their baffle is only a single part, it shouldn't fall under the NFA. Where a combination of loose baffles would be considered multiple 'parts'.

Sig could also ague that this baffle isn't 'only' for use in said assembly, since it is used as a brake.

NRA Life Member, NRA Certified Instructor: HFS, Pistol, Rifle, PPIH,PPOH
Suarez Combat Arms Instructor School
Admit nothing. Deny everything. Demand proof.
If we lie to the government, it's a crime. If the government lies to the people, it's called politics.
Paying for welfare is slavery.

The term “Firearm Silencer” or “Firearm Muffler” means any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for the use in assembling or fabricating a firearm silencer or firearm muffler, any part intended only for use in such assembly or fabrication.

Ok, so using the Feds definition, Sig is basing their argument on the word 'parts'. Since their baffle is only a single part, it shouldn't fall under the NFA. Where a combination of loose baffles would be considered multiple 'parts'.

So this has me thinking, with the recent determination with the SB15 arm brace not making a pistol an SBR, what's to stop someone making a muzzle device designed and intended to be used in another way but happens to make a great sound suppressor if used in a manner in which it wasn't designed?

The term “Firearm Silencer” or “Firearm Muffler” means any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for the use in assembling or fabricating a firearm silencer or firearm muffler, any part intended only for use in such assembly or fabrication.

Ok, so using the Feds definition, Sig is basing their argument on the word 'parts'. Since their baffle is only a single part, it shouldn't fall under the NFA. Where a combination of loose baffles would be considered multiple 'parts'.

Sig could also ague that this baffle isn't 'only' for use in said assembly, since it is used as a brake.

Sorry, I was wrong. I looked into it again, Sig is claiming it does not fall into the definition of silencer because the part is not intended ONLY for use in a silencer, as the definition requires. They are arguing that it also is intended to be used as a muzzle brake.